Self-cleaning photographic transparency processing and projection system

ABSTRACT

A photographic system, comprising a film cassette having a strip of film extending through a film gate, a supply of processing composition, and a processor for applying the processing composition to the film upon manipulation of the film in the cassette; and a film drive and projection system adapted to receive the cassette, having an aperture plate adapted to mate with the film gate, and comprising a mechanism for manipulating the film to cause processing, and an absorbent pad on the film strip in position to engage the aperture plate and clean it after the film has been processed.

United States Patent [191 Land [ Nov. 19, 1974 [75] Inventor:

[ SELF-CLEANING PHOTOGRAPHIC TRANSPARENCY PROCESSING AND PROJECTIONSYSTEM Edwin H. Land, Cambridge, Mass.

[73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: Oct. 31, 1973 [21] Appl. No.: 411,314

Related US. Application Data [62] Division of Ser. No. 261,153, June 9,1972.

3,514,047 5/1970 Mallie et al. 15/210 R X 3,778,140 12/1973 3,785,7251/1974 3,789,452 2/1974 Nemoto 15/210 R Primary ExaminerFred L. BraunAssistant Examiner-E. M. O'Connor Attorney, Agent, or Firm-John W.Ericson [5 7] ABSTRACT Q A photographic system, comprising a filmcassette having a strip of film extending through a film gate, a supplyof processing composition, and a processor for applying the processingcomposition to the film upon manipulation of the film in the cassette;and a film drive and projection system adapted to receive the cassette,having an aperture plate adapted to mate with the film gate, andcomprising a mechanism for manipulating the film to cause processing,and an ab- [56] References Cited sorbent pad on the film strip inposition to engage the UNITED STATES PATENTS aperture plate and clean itafter the film has been pro- 2,606,409 8/1952 Gordon 274/47 cessed,2,992,447 7/1961 Hicks 15/210 R 3,293,682 12/1966 Giles 15/210 R 3Clams, ll Drawmg Flgures as a so 1 so 5 e SEES L- I! .7 gn =9 38 u a l:{I I II": a in: I'//I a I: 35

TAKEUPREEL Uuununnl u SELF-CLEANING PHOTOGRAPHIC TRANSPARENCY PROCESSINGAND PROJECTION SYSTEM This is a division of application Ser. No.261,153, filed June 9, 1972.

This invention relates to photography, and particularly to a novelself-cleaning system for processing and projecting transparencies.

A recent advance in photography has been the creation of systems,especially useful for the production of motion pictures, in which thefilm in a cassette containing a film processor is exposed, and thenprocessed and projected in apparatus which manipulates the film toactuate the processor. Such a system is disclosed in US. Application forLetters Patent Ser. No. 227,080, filed on Feb. 17, 1972 by Edwin H. Landfor Photographic System for Processing and Projecting Transparencies,and assigned to the assignee of this application.

In the system described in the above-cited application, an initiallysealed container of processing composition is opened, and then coated onthe film as the film is wound onto a reel. The amount of processingcomposition is selected to be exhausted at the end of the coatingprocess. Usually, all of the composition is applied to the film, anddries on the film; the drying process is aided by projection of thefilm, with some attendant heating by the projection lamp, immediatelyafter processing. However, an occasional drop or so of processingcomposition may find its way onto elements of the system other than thefilm.

There is a spring biased pressure plate in the cassette, which engagesthe emulsion side of the film in the region of a film gate through whichthe film passes for exposure and projection. Should processingcomposition get onto this plate, it could cause spots, smears orswelling of the emulsion on film coming into contact with the platebehind the film from which the composition was deposited, or it mightdry while the film was motionless, and cause sticking of the film.

Another potentially troublesome area is the aperture plate in the filmdrive and projection system. The aperture plate is a generallyrectangular block adapted to register with the film gate in a cassetteand to engage the film; it is formed with a framing aperture thatdefines the optical boundaries of the projected frame. Either anoccasional drop of processing composition, or particles of lint or dust,deposited by cassettes on this plate would be particularly troublesome.Any problems caused in a cassette by its own leakage tend to be minorand self-limiting; however, even minor contaminations of the apertureplate by each of a succession of cassettes are cumulative.

It would manifestly be desirable to inhibit both the self contaminationof cassettes, and the progressive contamination of the aperture plate bycassettes, in systems of the kind here described. The object of thisinvention is to minimize the effects of such contamination, withoutmaking extensive modifications of the apparatus or requiring onerousmanual cleaning procedures.

The above and other objects of the invention are attained by attachingone or more pads of relatively soft, absorbent and preferably brush-likematerial to a film strip otherwise adapted for use in a system of thekind shown and described in the above-cited copending application Ser.No. 227,080. In accordance with a presently preferred embodiment of theinvention, only one such pad is employed, and that is placed on thenonemulsion side of the film and used to clean the aperture plate in thefilm drive and projection system just before the cassette is ejected.However, as will appear, it is within the scope of the invention in itsbroader aspects to employ an additional pad, on the emulsion side of thefilm, to clean the pressure plate in the cassette after the film isprojected, or to employ more than one pad for either or both purposes.

In the transparency processing and projection system described in theabove-cited copending application Ser. No. 227,080, a cassettecontaining exposed but unprocessed film is carried through a sequence offour operational stages. First, the film is advanced, in the directionin which it was advanced between exposures in the camera, to a pointbeyond the exposure termination point. This process has two significantadvantages, and is used to perform an enabling step in the filmprocessing operation. One advantage is that the processing compositionis always applied to the same length of film, even though the film mayhave been removed from the camera before all of it was exposed. Thatmakes it possible to use up all of the processing composition suppliedwith the cassette by applying it to the film, thus minimizing thechances of leakage. Secondly, the construction of the film drive andprojection system is simplified because the basic operational cycle ofadvancing and then rewinding the film is the same whether the film isinitially processed or unprocessed; for unprocessed film, as willappear, this basic cycle is simply repeated.

As fully described in the above-cited copending application Ser. No.227,080, processing composition is applied to the film as it is rewoundafter the advance movementjust described. During this process, the filmis engaged by coating apparatus, which imposes a drag on the drivemechanism. This mechanism includes slip clutches, and the slipping ofthese clutches provides signals used to advance the system to its nextoperational phase. Accordingly, it is undesirable to impose anyadditional drag on the film during the coating operation.

The processing operation is terminated when an aperture in the filmengages a cam and valve member forming a part of the processor and movesit into a latched position in which the coating elements of theprocessor are disengaged from the film. The film cannot move beyond thefinal position of the cam and valve member until it is disengaged fromthat member when the film is advanced for projection; accordingly, aclutch in the drive mechanism slips at that point, and a signal isproduced that causes the advance for projection to begin.

In accordance with the invention, the aperture plate cleaning pad ismounted on the film in a location that will not encounter the apertureplate during the operations described above. The reason is that properoperation of the cleaning pad necessarily requires the application of adrag force to the film which might interfere with the operation of thesystem during processing.

In particular, the cleaning pad is preferably located on the leader ofthe film far enough from the aperture that ends the processing cycle sothat it will not engage the aperture plate when rewinding of the film isterminated by engagement of the film aperture with the cam and valvemember in the final position of the cam and valve member.

During the final rewinding operation, which takes place after the filmhas been projected, the film aperture passes the cam and valve memberwith clearance, and rewind does not terminate until the end of the filmis reached. During that additional rewinding movement, the cleaning padencounters the aperture plate, removing any stray processingcomposition, orother foreign matter such as lint or dust or the like,just before the cassette is ejected. The cleaning operation is repeatedeach time the cassette is returned to the film drive and projectionsystem for projection and rewinding, so that in normal use the apertureplate is cleaned frequently relative to the times when it is subjectedto possible contamination by processing composition.

The apparatus of the invention, and its mode of operation, will best beunderstood in the light of the following detailed description, togetherwith the accompanying drawings, of variousillustrative embodiments ofthe invention.

IN THE DRAWINGS,

FIG. I is a schematic perspective sketch of a film cassette shown inassociation with a film drive and projection system adapted to embodythe invention;

FIG. 2 is a schematic elevational view, with parts shown in crosssection and parts broken away, of the film drive and projection systemof FIG. 1, taken substantially along the lines 2-2 in FIG. 1;

FIG. 3 is a schematic fragmentary perspective sketch of a portion of acassette receiving receptacle in the film drive and projection system ofFIG. 1, taken substantially along the lines 33 in FIG. 1;

FIG. 4 is a fragmentary schematic plan sketch, with parts broken away,of a film strip in accordance with the invention and forming a part ofthe cassette of FIG.

FIG. 5 is a fragmentary schematic cross-sectional view of a portion ofthe film strip of FIG. 4, taken essentially along the lines 55 in FIG.4; FIG. 6 is a fragmentary schematic elevational view of a portion ofthe film strip of FIG. 4, taken essentially along the lines 66 in FIG.4;

FIG. 7 is a fragmentary schematic elevational view of a portion of afilm strip in accordance with a modification of the invention;

FIG. 8 is a fragmentary schematic elevational view of a portion of afilm strip in accordance with another modification of the invention;

FIG. 9 is a schematic perspective sketch of a cassette adapted for usein accordance with the invention;

FIG. 10 is a schematic plan sketch, with parts omitted, parts shown incross section, and parts broken away, of a film cassette adapted for usein accordance with the invention; and

FIG. 11 is a fragmentary schematic elevational sketch of a portion ofthe film drive and projection system of FIG. I shown in association witha portion of the cassette of FIG. I, with parts omitted, parts shown incross section, and parts broken away.

FIG. I shows the external cooperative aspects of a system adapted toembody the invention. Except in the particular respects to be described,the system may be identical with that shown and described in theabovecited copending application Ser. No. 227,080, to which reference ismade for a detailed description. Accordingly, the system will be heredescribed only to the extent necessary for an understanding of theinvention.

The basic elements of this system are a cassette 1, adapted to beinserted in a pocket 2 formed in the outer 5 housing 3 of a film driveand projection system generally designated 4. A strip of film in thecassette has ends connected to supply and takeup reels rotatably mountedin the housing of the cassette to move the film back and forth through afilm gate in the housing, as will appear. A translucent viewing screen5, on which projected images at times appear, is mounted at the front ofthe housing 3.

As best shown in FIG. 2, the pocket 2 has a floor 6 on which an apertureplate 7 is mounted. The aperture plate 7 is adapted to extend into thecassette such as I and there register with the film in the cassette.Light supplied in a manner to be described passes through the film, andthence over a path traversing a suitable framing aperture in theaperture plate 7, a cooperating recess in the floor 6, a blinder housing8, and a conventional shutter 9, to a lens 10. As described in theabovecited copending application Ser. No. 227,080, the blinder housingreceives a blinder that serves at times to close the optical paththrough the aperture in the ap erture plate 7 and thereby assist inproviding a lighttight environment for the film in the cassette, whileit is being processed. The lens focuses an image of the portion of thefilm selected by the framing aperture on a mirror 11, whence it isreflected to the screen 5.

As shown in FIG. I, the cassette 1 is provided with a number oflight-baffled openings, 12,13, 14, I5 and 16. These openings exposeparts adapted to cooperate with corresponding parts of the film driveand projection system to perform various functions in the cassette.Thus, a sprocket formed on the takeup reel mentioned above is accessiblethrough the opening 12. A similar drive sprocket formed on the supplyreel is accessible through the opening 13. Projection light is at timesadmitted to the cassette through the opening I4. A stop can enter, tobrake a snubber roll forming a part of the cassette, through the opening15. The opening 16 serves to admit a locating pin, forming a part of thefilm drive and projection system, to register the presence of a cassettein the system and to enable the processing apparatus in a mannerdescribed in detail in the above-cited copending application Ser. No.227,080.

A flange 17 is formed on the upper end of the cassette I. This flangeaids in grasping the cassette while inserting it in, or removing itfrom, the pocket 2. It also helps to fix the cassette in position in thefilm drive and projection system, by engagement with the rim of thepocket 2.

Referring to FIG. 3, parts adapted to enter the openings in the cassetteI are adapted to enter the pocket 2 through corresponding openings in aside wall 18 of the pocket. Drive sprockets for the supply and takeupreels are adapted to enter through openings 19 and 20, respectively. Alight beam for projection enters through an opening 21. The locating pinenters through an opening 22. The snubber roll stop enters through anopening 23.

In addition to the aperture plate 7 described above, the actuating arm24 of a normally closed switch S1 is movably mounted on the floor plate6. This switch is adapted to be opened when a cassette is inserted inthe pocket 2, to interrupt a restoring circuit that resets the apparatusto its standby condition if it is inadvertently started without acassette in the pocket, as described in. the above-cited copendingapplication Ser. No. 227,080.

A foot pedal is movably mounted in the pocket 2 to be depressed by theinsertion of a cassette. The foot pedal is connected to an actuating armextending through the floor plate 6, to release the locating pin asdescribed in the above-cited application Ser. No. 227,080.

The photographic system of the invention preferably makes use of aphotofinishing process in which a strip of film, following exposure inthe camera, is contacted with a single processing composition to form afinished transparency from the latent image or images formed on the filmduring its exposure. The physical construction of such film, the natureof the photosensitive coating thereon, and suitable processingcompositions therefor, are described in the above-cited copendingapplication Ser. No. 227,080. However, the physical construction of thefilm strip is modified in accordance with the invention in a manner nextto be described.

Referring to FIG. 4, there is shown a film strip generally designated26, which comprises a leader 27 terminating at an end formedwith anaperture such as 28. The aperture 28 serves to connect that end of thefilm to a takeup reel, to be described.

Behind the leader, which may be in the neighborhood of l8 inches inlength, there is a strip 29 of photographically useful film, upon whichprojectable images may be formed. The strip 29 may be, for example,approximately 52 feet in length for 8 mm film.

Following the photographically useful portion of the film is a trailerregion generally designated 30. The trailer 30 terminates at another endformed with an aperture by means of which that end of the film isadapted to be connected to a supply reel, to be described.

The film 26 may comprise a base of any suitable transparent material ofthe kind conventionally used for film bases. On this base is applied, atleast over the central portion ofthe photographically usable length ofthe film 29, an emulsion comprising a photosensitive coating, whereon aseries of latent images may be formed with a camera. The photosensitivecoating is preferably of one of the forms, described in the abovecitedcopending application Ser. No. 227,080, which can subsequently beprocessed to form a projectable image on the film base.

It should be noted that the invention is not directed to the chemistryby which images are developed in a photosensitive emulsion andtransferred to an image receiving stratum. However, in the practice ofthe invention, whether the film employed is black and white or colorfilm, at the present time the preferred embodiment of the inventionemploys film ofa type not requiring the removal of a negative emulsionafter it is developed.

Referring again to FIG. 4, the film 26 is formed along one edge withsprocket holes such as 38 at regular intervals adapted to cooperate witha drive pawl, in a manner to be described, in either camera orprojector, for incremental advancement of the film. The series ofsprocket holes 38 adjacent the trailing end of the film may beinterrupted by a first elongated sprocket hole 39. This elongated hole39 may span, for example, two of the sprocket holes 38.

Further along the film in the direction of the supply reel end, theseries of sprocket holes 38 is again interrupted by a second elongatedsprocket hole 40, longer than the sprocket hole 39 and, for example,spanning three of the sprocket holes 38. As will appear, the firstelongated sprocket hole 39 establishes an exposure end point in thecamera, whereas the second sprocket hole 40 determines a film takeuptermination point in the film drive and projection apparatus to bedescribed.

Basically, termination of film advance at the first elongated sprockethole 39 is attained by the use of a single drive pawl in the camera,which sequentially engages the sprocket holes 38 to advance the film byone frame length in a conventional manner. Toward the end of each suchadvance stroke, as is conventional, the pawl is cammed down'out ofengagement with the film. When the single pawl engages the elongatedaperture 39, the camming down movement occurs before the film engagesthe leading edge of the elongated hole, and therefore the pawl may cyclerepeatedly without further advance of the film. This serves to effect atermination of film advance for the purposes of exposure adjacent theend of the region of photographically useful emulsion, to alert thephotographer, by the somewhat different sound produced when the pawlskips the film, that his cassette should be replaced.

The film drive and projection system is provided with a double pawl,comprising two integral pawls spaced apart by one frame length, eachpawl being of the same shape as the single pawl in the camera. When thefirst elongated aperture 39 is encountered, the trailing pawl of thepair serves to engage the leading edge of the aperture 39 to cause thefilm to be advanced without interruption. For normally spaced sprocketholes 38, both of the pawls engage the film in sequential sprocketholes. However, when the second elongated sprocket hole 40 isencountered, the pawls will pass through it without film engagement, andthereby terminate film advance in the same manner as did the single pawlupon engagement of the double length sprocket hole 39.

Formed on the trailing end 30 of the film 26, beyond the exposureadvance termination portion just described in the direction of thesupply reel end of the film 26, is a singularity generally designated 41comprising a detent engaging element here shown as an aperture 42 formedin the film, adjacent which a projecting bump 43 is formed, as bypressure, heat and pressure, or the like. As best shown in FIG. 5, thesingularity 41 thus comprises a hook adapted to engage the detent in theform ofa process control actuating element, to be described, as the filmis moved with respect to the detent in the direction of the takeup reel.

The bump 43 forming a part of the detent engaging assembly 41 in FIG. 4projects from the film, and might be deformed, or might cause pressuremarks on other parts of the film, as it is wound on the reel. To avoidthat result, it is preferred to provide suitable pockets, not shown,comprising apertures formed in the trailing end 30 of the film, andspaced at suitable intervals with respect to the radius of the supplyreel spool to receive the projection 43 as the film is wound onto thereel. This provision allows the film to be evenly wound on the spool,without'deformation of the bump.

Formed on the leader end 27 of the film 26 is another detent engagingmeans, here shown as an aperture 44 in the central region of the film.This aperture serves to actuate a valve member forming a part of theprocessing apparatus to be described, for purposes to appear.

As shown in FIGS. 4 and 6, an aperture plate cleaning pad 45 is securedto the non-emulsion side of the film strip 26 on the film leader 27,between the apertures 28 and 44. The paid 45 may be cemented to thefilm, and may be of any suitable absorbent, resilient and preferablybrush-like material, such as any conventional flocked fabric of naturalor synthetic fibers. In order to enter and engage the edges of theaperture in the plate 7, the pad 45 may be formed with one or moreraised portions 153, as by embossing under pressure, or the like.

The length of the pad 45 is preferably selected to be somewhat less thanthe circumference of the film on the takeup reel in the region on whichit is wound, in order to allow the balance of the film strip to be woundevenly on the reel. The pad 45 is preferably located at a distance Xfrom the aperture 44 selected to cause the pad to stop short of the filmgate in the cassette, to be described, when film movement toward thesupply reel is terminated by engagement of the aperture 44 with thevalve member in the cassette, to be described. The distance X shouldalso be selected relative to the end of the strip at which the aperture28 is formed so that the pad 45 will sweep the aperture plate 7 when thefilm is rewound to the termination point established by the end of thefilm connected to the takeup reel.

If desired, a pressure plate cleaning pad 46, of the same material asthe aperture plate cleaning pad 45, may be secured to the emulsion sideof the film in position to clean the aperture plate of the cassette, tobe described, immediately following the projection of the film. For thatpurpose, the pad 46 may be located in the vicinity of the secondelongated sprocket hole 40 so that it will enter the film gate and sweepthe pressure pad at the end of the projection cycle.

Alternatively, as shown in FIG. 7, the pressure plate cleaning pad 46amay be located on the film 26 opposite the aperture plate cleaning pad45. By that arrangement, both the pressure plate and the aperture platewill be cleaned as the last step before the cassette is ejected.

The arrangement shown in FIG. 7 gives the maximum brushing pressure fora given thickness of each of the cleaning pads 45 and 460, but mayrequire undue force for a desired thickness, and therefore fluidabsorbing capacity, of the pads. In order to allow more pad thicknessfor the same film drag, the construction shown in FIG. 8 may be adopted.As there shown, the aperture plate cleaning pad 45a and the pressureplate cleaning pad 46b may be sequentially located on opposite sides ofthe film 26, with the pad 461) on the emulsion side. The pad 46b shouldbe between the pad 45a and the film aperture 44 in the position of thepad 45 in FIG. 4. The leader of the film should be extended so that bothpads will pass through the film gate when the film is rewound afterprojection. By that arrangement, the pressure plate is first cleaned,and the aperture plate is then cleaned just before the cassette isejected.

The length of each pad may be the same as the length of the pad 45 inFIG. 4, with allowances so that the remaining film can be smoothly woundin the takeup reel. If desired, the leading and trailing edges of thepads may be tapered to facilitate entry, as shown at 47, 48, 49 and 50in FIG. 8.

FIGS. 9 and 10 show, in part fragmentarily, and in part schematically,the pertinent elements of an internally programmed cassette 1 adaptedfor use in the system. of the invention. The cassette comprises ahousing formed of any suitable opaque material such as metal, plastic,or the like, and preferably manufactured in two cooperating parts.

Asshown in FIGS. 9 and 10, the housing parts com- 4 prise a basegenerally designed 51, comprising side walls 52 and a base plate 53. Thebase plate 53 extends across the base of the wall 52, and comprises oneside of the housing. The walls 52 extend at least in part about theperiphery of the base plate 53, and cooperate with interfitted walls 54of a cover generally designated 55. The walls 54 overlap thecorresponding segments of the walls 52 to form the sides of the housingof the cassette 1.

A cover plate 56 is formed integral with the walls 48, and completes theupper side of the housing as seen in FIGS. 9 and 10. When the cover isplaced in position, it may be formed integral with the base 55 by heatsealing, or by a suitable adhesive, or the like.

The base andv cover parts form, when assembled, the end flange 17 thatserves to support and locate the cassette l in either a camera, or inthe film drive and projection system of FIG. 1.

Rotatably disposed within the cassette housing is a supply reelgenerally designated 57. The reel 57 is provided with an upper flange 58and a corresponding lower flange, not shown in FIG. 10, to guide thefilm strip 26 as it is wound about the spool-portion of the reel 57, notshown, to which the supply end 30 of the film 26 (FIG. 4) is attached.

A sprocket schematically indicated at 59 may be formed integral with thereel 57 to adapt the reel to be driven about its axis of rotation.Access to the sprocket 59 may be provided through the aperture 13 in thecover plate 50 (FIG. 1), light-baffled by suitable conventional annularflanges formed in cooperating relation on the cover plate 56 and on theupper surface of the flange 58, as at 60. The lower flange of the reel57 may be formed in a conventional manner with a cylindrical axialopening to receive a cooperating axle, not

shown, formed integral with the base plate 53.

Initially, the film 26 is in its unexposed state and coiled primarilyabout the supply reel 57. It is shown in FIG. 10 in the position assumedas it nears the end of its movement away from the supply reel, as towardthe end of exposure in a camera, in which it is nearly exhausted fromthe reel 57.

In its path from the supply reel 57, the film 26 first encounters abobulator roll 61. The film engages a portion of the periphery of thebobulator roll, as shown, and passes therefrom around a conventionalidler roll 62 journalled for rotation in the housing, and thence throughfilm processing means, to be described below. In addition to theapparatus for processing the film in a manner to be described, the filmprocessing means comprises a signal generator for producing an externalcondition signal on terminals schematically indicated at 63 and 64, toindicate whether or not the processing means has been actuated.

Beyond its path through the film processing means, the film 26 extendsthrough a conventional lightbaffled aperture schematically indicated at65 and forming a portion ofa film gate in the housing. The film 26reenters the housing through a second light-baffled aperture generallydesignated 66 and comprising a second portion of the film gate.

The film 26 next passes over a conventional snubber roll, generallydesignated 67, and finally passes to a takeup reel generally designated68, comprising a spool portion to which the takeup reel end of the filmis connected, and about which the film is wound as suggested in FIG. 10.

In addition to parts corresponding to those parts described inconnection with the supply reel 57, the takeup reel comprises anexternal upper flange 69 protruding beyond the maximum radius of thefilm 26 when substantially stored on the takeup reel. On the flange 69is formed a suitable drive sprocket 70, by

means of which the film can be selectively advanced in r a manner to bedescribed.

The bobulator may be of any conventional construction suitable for theperformance of the known function of isolating the film drive pawlassociated with the camera, or the pawl associated with the projector,from the inertia of the supply reel 57. However, it is preferably of theform shown, in which the bobulator roll 61 is journalled on a pin 71 forrotation by the film.

The pin 71 is formed integral with a support 72 of plastic or the like.The support 72 is journalled to the base plate 53 by means ofa pin 73formed integral with the base plate, and biased by a spring 74 formedintegral with the support 72. The spring 74 acts against a post 75formed integral with the base plate 53. The bobulator roll 61 can thusboth rotate about the pin 71, and move backwards and forwards in thedirections of the double arrow shown in FIG. 10.

The bobulator roll responds to increases or decreases in the tension ofthe film 26 by temporarily shortening or lengthening the film path,respectively. Such changes in film tension are produced by the actuationof the film drive pawl, and are determined by the inertial forcesexerted by the supply reel 57, together with the larger or smallersupply of film that may be on it at any given time. By that arrangement,as the film is advanced incrementally by the pawl associated with thecamera or projector, it can rapidly move the bobulator roll against thespring 74 without immediately affecting the supply reel, which can thenmore or less gradually allow the bobulator roll to relax while supplyingthe segment of film taken by the pawl.

A lighttight shield around the film gate formed by the apertures 75 and66 is formed by a wall portion 76 formed integral with the base plate 53and made integral with the cover plate 56 after assembly of the parts inthe manner described above. An exposed chamber behind the film 26 isthus formed for the purpose of admitting projection light.

The apparatus for this purpose is conventional, and will only briefly bedescribed. In short, it comprises a prism generally designated 77 andcomprising a mirror, not shown, but disposed at 45 to the plane of FIG.10. As schematically indicated, the prism 77 is mounted betweenextensions 78 formed on the wall 76.

Light enters the cassette through the port 14 formed in the cover plate56 in directions normal to the plane of FIG. 10. The mirror in the prism77 directs this light downwardly through the film 26 in the film gatefor the projection of images on the film through the lens 10 (FIG. 2).

Also disposed in the chamber bounded by the wall member 76 and the filmpassing through the film gate is a conventional pressure plate 79,located between the prism and the film, and biased by a spring 80 intoengagement with the film. The spring 80 is supported and retained bysuitably shaped extensions of the support wall 76, as shown.

The pressure plate serves in the conventional manner to cooperate with acamera, by locating the focal plane of the film during exposure. Anaperture 81 is provided in the pressure plate 79, as schematicallyindicated, to pass light entering through the prism assembly 77 througha selected frame of the film 26, after the film is processed in a mannerto be described. It is preferred that the aperture 81 be somewhat largerthan the frame to be projected so that the aperture in the apertureplate 7 (FIGS. 2 and 3) serves as the limiting aperture bounding theprojected frame.

The snubber roll 67 may also be of entirely conventional construction.As illustrated, it is provided with a hub portion schematicallyindicated at 82 that is adapted to protrude through the (suitablylight-baffied) aperture 15 in the cover panel 50 for engagement by astop member, comprising a part of either the camera or of the film driveand projection system, that is engaged when the film is to beincrementally advanced by a pawl for exposure or projection purposes.The cooperation between the snubber roll 67 and the takeup reel 68 isconventional, but will be briefly described.

The drive sprockets 59 and of the supply and takeup reels 57 and 68,respectively, are adapted to be engaged by corresponding drive sprocketscomprising a part of a camera, or of-the film drive and projectionapparatus described in the above-cited copending application Ser. No.227,080. In the film drive and projection apparatus, both supply andtakeup reels are adapted to be driven through slip clutches. In thecamera, only a drive for the takeup reel need be provided. This drivecomprises a slip clutch connected to a sprocket driving the takeup reeldrive sprocket 70, in cooperation with a drive pawl for sequentiallyengaging a series of the sprocket holes 38 formed in the film 26, alonga portion of the edge of the film in the film gate between the apertures65 and 66.

When the snubber roll 67 is stopped by engagement of the hub 82 asdescribed above, operation of either the camera or of the film drive andprojection system to incrementally advance the film towards the takeupreel, by engagement of a pawl with the sprocket holes in the film 26,will momentarily loosen the film from engagement with the stationarysnubber roll 67 and allow the slip clutch driving the takeup reel 68 totakeup that increment of the film advanced by the pawl. Betweenengagements of the pawl, the slip clutch prevents the takeup reel fromadvancing the film.

In the film drive and projection system, the snubber roll 67 is engagedonly while the film is to be incrementally advanced onto the takeupreel. When the film is rewound onto the supply reel, the snubber roll 67is disengaged and acts as an idler. As will appear, that may occureither during the processing of the film while rewinding, or duringsubsequent rewinding of the processed film after projection.

The film processing means, described in detail in the above-citedcopending application Ser. No. 227,080, will next be briefly described,with reference to FIG. 10. As there shown, the apparatus generallycomprises wall means comprising portions of, or formed integral with,the base plate 53 and the cover plate 56, which serve to guide, supportand house the various elements of the processing apparatus to bedescribed. These walls form an outer film composition containing housinggenerally designated 83, defining a chamber in which there is mounted aninitially sealed container generally designated 84 of processingcomposition. The container 83 communicates with a coating nozzlegenerally designated 85. These elements are mounted above the plane ofthe film 26.

Principally located below, but in part surrounding, the film 26 is apressure pad generally designated 86. The pressure pad is acted on by aspring generally designated 87.

The basic elements of the processing station further comprise a combinedpressure pad deflection cam and nozzle closure valve member generallydesignated 88, and a pair of electrical contacts formed integral withthe, external terminals 63 and 64. The terminals 63 and 64 cooperatewith the cam and valve assembly 88 in a manner to be described below toprovide a signal indicating whether or not the film 26 has beenprocessed.

More specifically, the outer container 83 comprises walls 89 formedintegral with the floor plate 53 and extending upwardly therefrom inFIG. 10. The walls 89 and floor plate 53 form a container open on a sidethat is closed by a cover panel fragmentarily shown at 90 of the samegeneral configuration as the region bounded by the walls 89 of thecontainer 63.

The panel 90 is preferably put in place prior to assembly of the cover56 with the base 53, and serves as a support for the top plate 56 afterfinal assembly. As schematically indicated, the walls 89 are formed withan upper lug 91, and a lower ledge portion 92, in each of which areformed locating recesses 93 and 94, respectively, adapted to receivecorresponding locating posts, not shown, formed on the inside of thecover panel 90 to aid in locating the panel 90 during its installationas the cover of the container 83.

The initially sealed container 84, mounted within the outer container83, comprises a tub-like receptacle 95, of a suitable plastic or thelike, selected to resist interaction with the processing composition, orpermeation thereof by ambient gases. The receptacle '95 initiallycontains a charge 96 of processing composition in an adequate amount toprocess the film 26.

The receptacle 95 is formed on an open side with a circumscribing flange97 adapted to fit into corresponding slots formed in the base plate 53and the cover panel 56. As shown in FIG. 10, the flange 97 rests againsta shoulder formed on the lug 91 at the upper end of the wall 89, andprojects over the ledge 92 formed at the lower end of the wall 89.

The container: 84 is sealed to initially contain the processingcomposition 96 by one end 98 of a tear-tab generally designated 99. Thetear-tab 99 may be made of any suitable form of plastic materialselected to resist the action of the composition 96, and to avoidinteraction therewith, as well as to prevent the diffusion into thecomposition of gases such as oxygen, carbon dioxide, carbon monoxide,water, oxides or hydrides of sulfur or nitrogen, or the like, that mightmodify its composition. The end 98 is sealed to the plane surface of theflange 97 surrounding the opening formed in the receptacle 95, andwithin the flange area extending into the mounting recesses describedabove, by any suitable means such as heat sealing, by a suitableadhesive, or the like.

The tear-tab 99 extends from the end 98 sealed to the receptacle backupon itself and out through an aperture 100 formed in the walls 89 to aprocessing composition release mechanism, not shown but described indetail in the above-cited copending application Ser. No. 227,080.

Outside of. the sealed container 84, the walls 89 define a chamber 101into which the processing composition 96 can flow when the tear-tab 99is partially detache'd from the receptacle 95. The-outer chamber 101communicates with the coating nozzle 85 by way of a downwardlyconverging section 102 that communicates with a downwardly converginginlet passage formed in the nozzle 85.

The coating nozzle 85 may be formed in a conventional manner, as byprecision molding or the like, from a suitable thermoplastic resinselected to form a dimensionally stable and accurate molding whoseworking surfaces can be kept to close tolerances. The most critical ofthese form a plane, generally U-shaped film engaging land 103 formed onthe base of the nozzle, and a doctor bar 104, lying across the bend ofthe U-shaped land, and recessed from it as shown in FIG. 10.

The depth to which the doctor bar is recessed is greatly exaggerated inFIGS. 15 and 16; it is selected to be twice the desired thickness towhich the coating composition is applied to the film 26. The filmengaging land 103 and the doctor bar 104 circumscribe a generallyrectangular outlet aperture formed in the nozzle and communicating witha downwardly converging passageway 106 through which the processingcomposition is received from the outer container 83, as described above.

The nozzle 85 is provided at the sides with posts 114 that provideguidance for the film in its path over the coating gap. These posts alsoserve at times to stop the nozzle closure plate portion of the element88, to be described.

When engaged with the film in the manner to be described below, the filmis adapted to pass over the nozzle outlet port and between the posts 114with the emulsion side of the film in engagement with the land 103.During this engagement, coating takes place while the film moves, sothat the emulsion surface leaves the ,coating aperture as it passes overthe doctor bar 104 and carries with it a coating of processingcomposition established by the depth to which the bar 104 is recessedabove the land 103.

The pressure pad 86 will next be described. The pressure pad is shown inFIG. 10 in the initial position assumed upon assembly of the cassetteand prior to processing of the film 26.

As shown in FIG. 10, the film 26 normally passes below the nozzle 85,and above a normally disengaged film engaging pad surface 116. The padsurface is formed on an upwardly extending and generally rectangularprotrusion in a base plate 117.

The pressure pad 86 may be made of any suitable conventional material,such as stainless steel or the like; The raised surface 116, formed bydie stamping or the like, is ground or otherwise finished with a filmengaging plane surface that is adapted to mate, through the film 26,with the plane of the land 103 of the nozzle and generally conform tothe working area of the nozzle 85 confined between the land 103 and thedoctor bar 104 and encompassing the rectangular opening through whichthe processing composition passes.

The pressure pad 86 is formed with an end 119 that is adapted to lightlyengage the base side of the film 26 in the initial position shown inFIG. 10, for purposes to appear. Formed adjacent the end 119 on theplate 117, and extending upwardly therefrom, are a pair of ears 120adapted to extend up past the film 26 on either side and to ultimatelyengage the underside of the nozzle 85.

The pressure pad 86 is formed at its other end with a pair of upstandingears 121 formed integral with the plate 117 and extending upwardly pastthe film in FIG. to engage a sloping ledge 122 formed in the lower sideof an extension 123 of the walls 76 and 89. The extension 123 is formedintegral with the base plate 53 and joins the wall 76 defining theprojection aperture.

The ears 121 initially hold the film engaging surface 116 of thepressure pad out of engagement with the film. As will appear, the ears121 of the pressure pad also serve at times as guides for the combinedpressure pad depressing cam and nozzle closure plate member 88, to bedescribed.

The base plate 117 of the pressure pad is divided to form a pair'of legs124 which are bent downwardly somewhat in the region of the ears 121 assuggested in FIG. 10. Between the legs 124 is formed a downwardlydepending hook element 125 that initially serves as a detent to hold thepressure pad 86 in an inactive position in the housing. For thatpurpose, the hook 125 is engaged in the initial position shown by anupwardly bent end 126 formed at the end of the spring 87.

The spring 87 comprises a base portion 127 that is cut out to clear abearing post 128 on which the idler roll 62 is journalled. The baseportion 127 is further provided with a pair of mounting apertures inwhich suitable fasteners, shown as a pair of screws 129, can pass forsecuring the base 127 to the base plate 53. From the base portion 127 aresilient spring arm 130 extends, in planes normal to the base, intoengagement with the film engaging portion of the pressure pad 86, andthence to its termination 126 initially engaged with the hook 125.

The pressure pad depressing cam and nozzle closure plate member 88 willnext be described. The assembly 88 comprises a plane base plate 132formed at one end 133 to cover the outlet port in the nozzle 85, in amanner to appear, to close the nozzle when the member 88 is moved intoengagement with the nozzle at the end of the processing operation.

Formed as orthogonal extensions on the sides of the base plate 132 are apair of cams 136 and 137 that serve at times to depress the pressurepad, described above, in a manner to appear below. The cam 136 isshorter than the cam 137, to facilitate threading of the film 26 duringassembly of the cassette.

Toward the left end of the plate 132, the cam 137 is formed with anormally extending arm that extends generally parallel to the plate 132and is formed with a pair of spring arm extensions 141 and 142. Thesearm extensions taper away from each other towards the ends, to allowentry of a film aperture in a manner to appear.

A central portion 143 is bent upwardly and away from leg extensionportions 145 of the base plate 132, to form a hook having as its upperportion the extension 143 and as its lower portions the arms 145. Thesehook elements initially engage a ledge portion 146 formed integral withthe base plate 53 to hold the assembly 88 in the position shown. In thatposition, the cams 136 and 137 extendinto and are guided by the ears121, and the nozzle closing plate end 133 of the assembly 88 confrontsbut does not engage a downwardly sloping guide ledge 147 formed on thewall extension 123 referred to above.

The upper spring arm 141, of the hook comprising that arm and the lowerarm 142 formed on the assembly88, lightly engages the base of the film26 in the initial position of the parts shown in FIG. 10. The upwardlybent end of the arm 141 thus serves as a unidirectional detent that isadapted to engage the aperture 44 in the film, in a manner to bedescribed below, towards the end of the processing cycle to bedescribed.

The cam portion 137 of the assembly 88, of metallic conducting material,cooperates with the terminals 63 and 64 to form a signal generatorindicating whether or not the film 26 has been processed. For thispurpose, in the initial position of the parts shown in FIG. 10 assumedbefore the processing cycle is started, the cam 137 bridges theterminals 63 and 64, indicating to the film drive and projectionapparatus, to be described, that the film is not processed.

At the end of the processing cycle, the assembly 88 will be carried tothe right in FIG. 10, opening the circuit path between the terminals 63and 64 to indicate that the film has been processed.

The tear-tab 99 extends out through the aperture in the outer container83 and thence over an idler 150 journalled for rotation in the housingby means schematically shown as a bearing post 152 formed integral withthe base plate 53. The tear-tab 99 passes from the idler 150 to atear-tab release mechanism, not shown, that is enabled by the insertionofa locating pin into the opening 16 and actuated by one of a set ofteeth 151 formed on the flanges of the supply reel 57 when the supplyreel is first rotated clockwise in FIG. 10 after the mechanism isenabled. The tear-tab release mechanism is fully shown and described inthe above-cited copending application Ser. No. 227,080.

Having described one embodiment of the cassette of the invention, itsoperation will next be described in connection with FIGS. 1-11.

Referring to FIG. 10, it will be assumed that an initially unexposedstrip of film 26 stored primarily on the supply reel 57 has been exposedin a camera, so that it has been advanced onto the takeup reel 68 to theexposure termination point determined by the first elongated sprockethole 39 in the film (FIG. 4). The teartab 99 will be in the positionshown in FIG. 10.

Next, assume that operation continues by the insertion of a locating pininto the port 16 of the cassette. As described in the above-citedcopending application Ser. No. 227,080, entry of the locating pin willenable the tear-tab release arm to engage the teeth such as 151 formedon the supply reel 57.

Next, assume that operation is continued by further rotation of thetakeup reel 68 counterclockwise, as seen in FIG. 10, to bring the film26 farther onto the takeup reel. During this rotation, the supply reel57 will move counterclockwise in FIG. 10, causing the teeth 151 to passthe tear-tab release arm without effective engagement therewith.

FIG. shows the parts of the coating station in their initial position,which is maintained during exposure of the film and during a portion ofthe first increment of motion just described, from the exposuretermination point toward the second termination point in which the filmis substantially exhausted from the supply reel, and in which the secondelongated sprocket hole 40 in FIG. 4 will be encountered. During theinterval of travel between those positions, and prior thereto, the camand nozzle closure plate assembly 88 is held in place by engagement ofthe arms 143 and 145 with the ledge 146, and the upper resilient arm 141of the film engaging hook formed on the assembly 88 is lightly engagingthe base of the film 26.

The pressure pad 86 is initially held in place by engagement of its hook125 with the detent 126 formed on the spring 87. In that position, theend 119 of the pressure pad 86 lightly engages the base of the film 26,and the ears 121 are in engagement with the ledge 122 formed on the wallsegment 123.

The parts of the coating station will remain in the position shown inFIG. 10 until, during the further advance of the film 26 towards thetakeup reel, the film engaging hook 43 approaches and engages the end119 formed on the pressure pad 86. When that occurs, near the secondtermination point established by the second elongated hole 40 in thefilm (FIG. 4), the hook 43 will move the pressure pad to the left inFIG. 10, to a position in which the ears 121 have moved out ofengagement with the ledge 122, and upwardly under the influence of thespring 87. The ears 120 on the pressure pad 86 will come into engagementwith the posts 114 forming a part of the nozzle 85, and the pressure pad86 will swing up into engagement with the film 26 and carry the emulsionside of the film into coating engagement with the nozzle 85. If apressure plate cleaning pad 46 is provided at the location shown in FIG.4, it will sweep the pressure plate as the second termination point isapproached and reached. However, the cleaning pad will perform no usefulfunction at this time, unless there is dust or lint on the pressureplate to be removed.

As the pressure pad 86 is moved to the left, the detent 126 formed onthe spring 87 will be disengaged by the hook 125. The purpose of thedetent 126 is primarily to prevent premature movement of the pressurepad 86 in the housing prior to its positive disengagement from theinitial position shown in FIG. 10 by the hook 43.

Next, assume that the first rewind operation is begun, by rotating thesupply reel 57 clockwise in FIG. 10. As described in the above-citedcopending application Ser. No. 227,080, this motion will bring the hook43 out of engagement with the end 119 of the pressure pad. The pressurepad will now urge the film 26 into coating engagement with the nozzle 85under the influence of the spring 87.

As the film 26 moves towards the supply reel 68, a pair of teeth 151 onthe supply reel will engage the teartab release arm, detaching thetear-tab 99 in part from the receptacle 95 to allow the composition 96to flow down into coatingengagement with the nozzle and the film 26.Preferably, as described in the above-cited copending application Ser.No. 227,080, the rewinding of the film is interrupted briefly, to allowthe composition to fill the nozzle, and then resumed. The compositionwill then be uniformly coated on the emulsion side of the film 26 to athickness determined by the doctor bar 104.

A doctor bar coater is preferred to other conventional forms of 'coatersfor the purpose of coating the film, because it is inherentlyinsensitive to changes in the viscosity of the processing compositionand to changes in linear film speed with respect to the doctor bar, overa reasonable range that makes the process relatively insensitive tothese variables. In particular, as is well known in the art in othercontexts, a doctor blade or doctor bar coater inherently will lay down auniform coating of one-half the distance between the doctor bar and thecoated substrate under conditions in which a uniform meniscus can beformed on the coating liquid adjacent its interface with the substrate.

The coating operation will continue until the composition 96 issubstantially exhausted and the film is stored substantially all on thesupply reel 68. Toward the end of that operation, the aperture 44 (FIG.4) will approach and engage the hook finger 141 formed on the valve andcam assembly 88. During the coating operation, it will be apparent thatno coated portion of the film passes through the film gate.

As the film 26 continues to move onto the supply reel, engagement of theaperture 44 in the film with the spring arm 141 will carry the filmalong the arm and downwardly, into the bight formed between the arms 141and 142. Further movement of the film 26 towards the supply reel willcarry the cam and valve member 88 to the right of the position shown inFIG. 10, causing the spring arms 143 and 145 to disengage the ledge 146,and bringing the cams 136 and 137 into contact with the base plate 117of the pressure pad 86 in the region of the ears 121, with the camassembly 88 being guided by the ears 121.

During this movement, the end 133 of the cam and valve assembly 88 isguided by the ledge 147 formed on the wall extension 111 of the housing,and moves below the nozzle towards a nozzle closing position. The

pressure pad 86 begins to move downwardly, out of engagement with thefilm 26. The film is still held down out of its normal plane of movementby engagement with the bight formed between the spring arms 141 and 142.

Movement in this direction will continue to move the assembly 88 to theright, as it goes to a final position in which the end 133 of the valveassembly 88 closes the nozzle 85 and shoulders formed on the assembly 88engage the stops 114 formed on the nozzle 85. In that position, thecleaning pad 45 is still in the housing on the takeup reel side of thefilm gate.

During its movement from the position shown in FIG. 10 to the finalposition just described, the cam 137 disengages the terminals 63 and 64,and thus provides a signal indicating that the film has been processed.

When the film is again moved toward the takeup reel, as duringprojection of the processed film, the aperture 44 will disengage the arm141, and the film will rise to its initial plane of movement, in whichit is free of all of the elements of the processing apparatus, forsubsequent cycles of projection and rewinding.

As described in the above-cited copending application Ser. No. 227,080,following a delay selected to permit the processing composition toaffect all of the film uniformly, the film drive and projectionapparatus will project the images just processed on a viewing screenwhile incrementally advancing the film onto the takeup reel.

The dual drive pawl in the film drive and projection system will advancethe film past the first elongated sprocket hole 17. Film advance isterminated when the second elongated sprocket hole 18 is encountered.

Next, the supply reel 57 will be driven to rewind the film until the endof the film on the takeup reel is encountered. As the film is moved pastthe position in which it was stopped by the closing of the cam and valvemember 88 at the end of the coating operation, the cleaning pad 45 willbe moved through the film gate. As shown in FIG. 11, the pad 45 willsweep the aperture plate 7, absorbing any processing composition thatmay have been deposited during projection. The extra thickness of thepad 45, greatly exaggerated in FIG. 11, will be absorbed by lifting ofthe pressure plate 79 against its spring 79. The pad 45 may remain inthe film gate at the end of the film motion, or pass through the gate tothe supply reel side of the housing.

When the end of the film on the takeup reel is reached, as described inthe above-cited copending application Ser. No. 227,080, the cassettewill be ejected for retrieval by the user. The aperture plate will beleft in clear condition for cooperation with the next cassette ofprocessed or unprocessed film.

While the invention has been described with reference to the particulardetails of preferred embodiments, many changes and variations will occurto those skilled in the art upon reading this description, and such canobviously be made without departing from the scope of the invention.

What is claimed is:

l. A photographic cassette, comprising an opaque housing, means forminga film gate in said housing, takeup and supply reels rotatably mountedin said housing, a strip of film having ends connected to said takeupand supply reels and extending therebetween through said film gate, saidfilm being initially unexposed and primarily coiled on said supply reel,said cassette being adapted to cooperate with a camera for selectiveexposure of portions of said film in said film gate as said film isadvanced onto said takeup reel to an exposure termination position,processing means in said housing responsive to manipulation of said filmin said housing following its initial advance from said supply reeltoward said takeup reel to said exposure termination position to applyprocessing composition to said film as it is first rewound onto saidsupply reel to a process termination position, said cassette beingadapted to cooperate with film drive and projection apparatus forsequential projection of portions of said film in said film gate as saidfilm is advanced onto said takeup reel to a projection terminationposition beyond said exposure termination position, and to be rewound toa rewind termination position on said supply reel beyond said processtermination point, and a cleaning pad of absorbent material mounted onsaid film in position to move through said film gate as said film movesfrom said process termination position to said rewind terminationposition.

2. A photographic film cassette comprising an opaque housing, meansforming a film gate in said housing, supply and takeup reels rotatablymounted in said housing, an elongated strip of film having a first endconnected to said takeup reel and a second end connected to said supplyreel and extending therebetween over a path through said film gate, saidfilm being initially unexposed and in a first position disposedprimarily on said supply reel, processing means in said housingengageable with said film and operable when engaged to apply processingcomposition to said film as said film is moved onto said supply reel,first actuating means on said film adjacent said second end for engagingsaid processing means as said film is advanced onto said takeup reel toa position primarily on said takeup reel, second actuating means on saidfilm adjacent said first end for disengaging said processing means assaid film is rewound onto said supply reel to a position primarily onsaid supply reel, and an aperture plate cleaning pad of absorbentmaterial mounted on said film between said first end and said secondactuating means in position to pass into and be exposed in said filmgate as said film is wound onto said supply reel beyond the position atwhich said processing means is disengaged by said second actuatingmeans.

3. The apparatus of claim 2, in which said cleaning pad comprises astrip of flocked fabric.

l =l =l

1. A photographic cassette, comprising an opaque housing, means forminga film gate in said housing, takeup and supply reels rotatably mountedin said housing, a strip of film having ends connected to said takeupand supply reels and extending therebetween through said film gate, saidfilm being initially unexposed and primarily coiled on said supply reel,said cassette being adapted to cooperate with a camera for selectiveexposure of portions of said film in said film gate as said film isadvanced onto said takeup reel to an exposure termination position,processing means in said housing responsive to manipulation of said filmin said housing following its initial advance from said supply reeltoward said takeup reel to said exposure termination position to applyprocessing composition to said film as it is first rewound onto saidsupply reel to a process termination position, said cassette beingadapted to cooperate with film drive and projection apparatus forsequential projection of portions of said film in said film gate as saidfilm is advanced onto said takeup reel to a projection terminationposition beyond said exposure termination position, and to be rewound toa rewind termination position on said supply reel beyond said processtermination point, and a cleaning pad of absorbent material mounted onsaid film in position to move through said film gate as said film movesfrom said process termination position to said rewind terminationposition.
 2. A photographic film cassette comprising an opaque housing,means forming a film gate in said housing, supply and takeup reelsrotatably mounted in said housing, an elongated strip of film having afirst end connected to said takeup reel and a second end connected tosaid supply reel and extending therebetween over a path through saidfilm gate, said film being initially unexposed and in a first positiondisposed primarily on said supply reel, processing means in said housingengageable with said film and operable when engaged to apply processingcomposition to said Film as said film is moved onto said supply reel,first actuating means on said film adjacent said second end for engagingsaid processing means as said film is advanced onto said takeup reel toa position primarily on said takeup reel, second actuating means on saidfilm adjacent said first end for disengaging said processing means assaid film is rewound onto said supply reel to a position primarily onsaid supply reel, and an aperture plate cleaning pad of absorbentmaterial mounted on said film between said first end and said secondactuating means in position to pass into and be exposed in said filmgate as said film is wound onto said supply reel beyond the position atwhich said processing means is disengaged by said second actuatingmeans.
 3. The apparatus of claim 2, in which said cleaning pad comprisesa strip of flocked fabric.